Thanks to BeckyEbook, I've found at least one such plugin, an unpublished FootnoteMoverX with such kind of code. There may be other(s) and I'll report it as soon as I bump on it. As I have been caught before, I determined that I would use permanently the standard layout.
Code:
# get proper endnotes href
if bk.launcher_version() >= 20190927 and not bk.epub_is_standard():
But, nevertheless, I fail to see the logic:
1. Sigil recommends this standard layout (it's even named "norme Sigil" in the French menu).
2. But it requires the user to perform one special step to implement it.
I read two days ago some comments from a French user who - wrongly - complained being confused with "virtual" paths in Sigil and even recommended to other users to rename ePub to zip and open this new zip file with 7zip to know the real path of the files. This is rubbish, but it shows that some users are still confused or uncertain about this choice.
Why require a special step, which some casual users may ignore, which some old users may forget, to follow a "Sigil norm" ? If there is no warning, it should belong to the Preferences settings. The least that could be expected from Sigil would be to make this choice trivial.
Determining what will be the architecture of the ePub, seems to be as important a subject as, say the display of entities. It's a major choice that should appear clearly.